Method for producing a thin film magnetic head

ABSTRACT

A longitudinal bias layer and an electrode layer are formed on a non-magnetic material layer. The longitudinal bias layer and the electrode layer are partially removed by an etching technique so that a narrow gap defining the track width Tw is formed in the longitudinal bias layer and the electrode layer. Furthermore, a three-layer film consisting of, from bottom to top, a magnetoresistance effect layer, a non-magnetic layer, and a transverse bias layer, or otherwise a spin valve film consisting of a free magnetic layer, a non-magnetic layer, a fixed magnetic layer and a bias layer is formed on the above structure. The three-layer film or the spin valve film is then partially removed by an etching technique so that the three-layer film or the spin valve film remains only in the above-described narrow gap formed in the longitudinal bias layer and the electrode layer. The shape of the side walls of the three-layer film or the spin valve film is precisely determined by the side walls of the longitudinal bias layer and the electrode layer. The resultant three-layer film or the spin valve film exhibits excellent magnetic detection characteristics. Furthermore, the longitudinal bias layer has good magnetic coupling with the magnetoresistance effect layer.

This application is a division of application Ser. No. 08/616,114, filedMar. 14, 1996, now U.S. Pat. No. 5,923,503.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thin-film magnetic head for use forexample as a floating type magnetic head in a hard disk device, which isdesigned to detect, by means of the magnetoresistance effect, a leakagemagnetic flux coming from a recording medium, and more particularly to athin-film magnetic head having a plurality of layers, which can beformed easily, and exhibiting improved performance in terms of detectinga magnetic field, and furthermore to a production method thereof.

2. Description of the Prior Art

FIGS. 12A to 12D are schematic diagrams illustrating a production methodof a conventional thin-film magnetic head based on themagneto-resistance effect. FIG. 13 is an enlarged sectional viewillustrating a part (the portion denoted by reference symbol XIII inFIG. 12D) of a thin-film magnetic head obtained after completion of theproduction process.

In a conventional method of producing a thin-film magnetic head, asshown in FIG. 12A, a three-layer film 2 is deposited, by means of forexample a sputtering technique, on a non-magnetic material layer (lowergap layer) 1 such as Al₂ O₃ formed on a lower shielding layer. As shownin an enlarged fashion in FIG. 13, the bottom layer of the three-layerfilm 2 serves as a transverse bias layer 2a for generating a transversebias field. The transverse bias layer 2a is a soft magnetic layer (SAL)made of a soft magnetic material such as an Fe--Ni--Nb(iron-nickel-niobium) alloy. The layer disposed on the transverse biaslayer 2a is a non-magnetic layer (shunt layer) 2b made of for example Ta(tantalum). The top layer is a magnetoresistance effect layer (MR layer)2c. The magnetoresistance effect layer 2c is made of for example aNi--Fe alloy.

A resist material is coated on the three-layer film 2 shown in FIG. 12A,and then subjected to an exposing and developing process using a deep-UVtechnique or the like thereby forming a resist layer 3 having a shapesuch as that shown in FIG. 12B. As shown in FIG. 12B, the resist layer 3has undercuts 3a, 3a formed at its lower positions on both sides. Thetrack width (TW) of the thin-film magnetic head is determined by thedimension of the resist layer 3.

The three-layer film 2, except regions on which the resist layer 3 isformed, is then removed using an etching technique such as an ionmilling technique, as shown in FIG. 12C. In this etching process, bothsides of the three-layer film 2 are removed, and slanted planes (i) areproduced. A longitudinal bias layer (hard bias layer) 4 and an electrodelayer 5 are then sputtered using the resist layer 3 as a mask so thatthese layers are formed only in the regions in which the three-layerfilm 2 is not formed. In the regions near the contacting interfacebetween the three-layer 2 and the longitudinal layer 4 and the electrodelayer 5, the thickness of the longitudinal layer 4 and the electrodelayer 5 changes in such a manner as shown in FIG. 13 due to theundercuts 3a, 3a formed on the sides of the resist layer 3.

After the resist layer 3 is removed, an upper gap of a non-magneticmaterial such as Al₂ O₃ is formed on the resultant multi-layer structureshown in FIG. 12D, and furthermore an upper shielding layer is formedthereon.

In this thin-film magnetic head, the longitudinal bias layer 4 is aso-called hard bias layer or a hard magnetic layer made of for exampleCo--Pt (cobalt-platinum) alloy. The magnetoresistance effect layer 2c ismagnetized in the X-direction into a single magnetic domain by amagnetic field maintained in the longitudinal bias layer 4. If adetection current is supplied to the magnetoresistance effect layer 2cfrom the electrode layer 5 via the longitudinal bias layer 4, a magneticfield is induced in the magnetoresistance effect layer 2c by thecurrent, and thus the transverse bias layer 2a experiences a magneticfield in the Y-direction originating from the magnetoresistance effectlayer 2c. As a result, the transverse bias layer 2a pinned magneticlayer is magnetized in the Y-direction. The transverse bias field in theY-direction in this transverse bias layer 2a is applied to themagnetoresistance effect layer 2c, and thus the uniform magnetizationperformed by the longitudinal bias field and the transverse bias fieldensure the linearity of the detection output relative to the change inthe leakage magnetic field in the Y-direction applied from a recordingmedium.

FIG. 14 is a front view of a conventional thin-film magnetic head of thespin valve type. The magnetic recording medium such as a hard disk movesin the Z-direction relative to this thin-film magnetic head, while theleakage magnetic field (external magnetic field) from the magneticrecording medium occurs in the Y-direction. The thin-film magnetic headshown in FIG. 14 includes a non-magnetic material layer (lower gaplayer) 1 formed of a non-magnetic material such as Al₂ O₃ (aluminumoxide), and a spin valve layer (SV) formed on the non-magnetic materiallayer, wherein the spin valve layer consists of 6 layers including alower non-magnetic layer 20 such as a Ta (tantalum), free magnetic layer21, non-magnetic conductive layer 22, fixed magnetic layer (pinnedmagnetic layer) 23, antiferromagnetic layer 24, and upper non-magneticlayer 25 such as Ta.

The lower non-magnetic layer 20 ensures that the free magnetic layer 21formed on the lower non-magnetic layer 20 can have uniform crystalorientation, and can have a low specific resistance. The free magneticlayer 21 and the fixed magnetic layer 23 are made of a Ni--Fe(nickel-iron) alloy. The antiferromagnetic layer 24 is a bias layer formaking the magnetization of the fixed magnetic layer 23 uniformly occurin the Y-direction. That is, anisotropic exchange coupling occurs at theinterface between the antiferromagnetic layer 6 and the fixed magneticlayer 23, and as a result the fixed magnetic layer 23 is magnetized inthe Y-direction (in the upward direction perpendicular to the drawingplane of FIG. 14) into a single magnetic domain. The antiferromagneticlayer 24 is made of an alloy such as Fe--Mn (iron-manganese), Ni--Mn(nickel-manganese), or Pt--Mn (platinum-manganese).

A longitudinal bias layer 4 such as a Co--Pt (cobalt-platinum) alloy isformed on both sides of the spin valve layer SV having the 6-layerstructure described above in such a manner that the longitudinal biaslayer is in contact at the contacting interface (V) with all six layersconstituting the spin valve layer SV. On the longitudinal bias layer 4,there is further disposed a layer made of a material having a smallspecific resistance, such as Cu (copper), Ta, or Cr (chromium).

In this thin-film magnetic head of the spin valve type, the longitudinalbias layer 4 is permanently magnetized in the X-direction, and the freemagnetic layer 21 is magnetized in the X-direction by a magnetic fieldfrom the permanently magnetized longitudinal bias layer 4. The fixedmagnetic layer 23 is magnetized in the Y-direction (the upward directionperpendicular to the drawing plane) by the antiferromagnetic layer 24. Asteady-state current flows from the electrode layer 5 to thelongitudinal bias layer 4 and further into the spin valve layer SVhaving the six-layer structure in the X-direction. If a magnetic fieldin the Y-direction is applied from a magnetic recording medium, themagnetization direction of the free magnetic layer 21 is inverted bythis external magnetic field from the X-direction to the Y-direction.The electric resistance of the spin valve layer SV changes depending onthe relationship between the magnetization direction of the freemagnetic layer 21 and the magnetization direction of the fixed magneticlayer 23. Therefore, it is possible to detect the leakage magnetic fieldfrom the magnetic recording medium by detecting the voltage dropassociated with the steady-state current.

The thin-film magnetic head shown in FIG. 14 can be produced as follows.First, the lower non-magnetic layer 20, free magnetic layer 21,non-magnetic conductive layer 22, fixed magnetic layer 23,antiferromagnetic layer 24, and upper non-magnetic layer 25 aresuccessively sputtered on the non-magnetic material layer 1 therebyforming the spin valve layer SV consisting of these six layers. The spinvalve layer SV is coated with a resist material. The resist is exposedto for example deep-UV light, and then developed so that a resistpattern having a width corresponding to the track width (TW) is formedon the spin valve layer SV. Using the resist pattern as a mask, The spinvalve layer SV is etched by means of for example an ion millingtechnique thereby removing the portions of the spin valve layer whichare not covered with the resist pattern. In this etching process, theshape of the resist layer formed by the deep-UV exposure and developmentprocess affects the shape of the cross section of the resultant spinvalve layer SV and thus the width between one contacting face (V) andthe other contacting face (V) increases with the contacting positionapproaching the bottom layer.

The longitudinal bias layer 4 is then formed by performing sputteringusing the resist layer remaining on the spin valve layer SV as a mask.Due to the shape of the resist pattern, the thickness of thelongitudinal bias layer 4 in the vicinities of the contacting interfaces(V) decreases with the contacting position approaching the top layer asshown in FIG. 14. Except for the vicinities of the contacting interfaces(V), the longitudinal bias layer 4 has a substantially constantthickness. The electrode layer 5 is then formed on the longitudinal biaslayer 4.

The thin-film magnetic head having the structure shown in FIG. 13 whichis produced according to the process shown in FIGS. 12A to 12D hasproblems as described below.

(a) In this thin-film magnetic head, the three-layer film 2 and thelongitudinal bias layer 4 are in contact at the slanted plane (j) witheach other. However, since the magnetoresistance effect layer 2c islocated at the top and the longitudinal bias layer 4 is located at thebottom, the longitudinal bias layer 4 in the region (ii) is not parallelto the magnetoresistance effect layer 2c extending in the X-direction.In order for the longitudinal bias layer 4 extending in a slanteddirection to magnetize the magnetoresistance effect layer 2c in theX-direction into a single magnetic domain along the plane (i), it isrequired that the longitudinal bias layer 4 have isotropic magneticcharacteristics. To achieve the isotropic characteristics, it isrequired to form the longitudinal bias layer 4 without introducingmagnetic strain. However, this requires difficult sputtering conditions.

(b) The angle and the length L in the X-direction of the slanted plane(i) of the three-layer film 2, and the thickness and the shape of thelongitudinal bias layer 4 in the region (ii) are all affected by theshape of the resist layer 3 formed in the process shown in FIG. 12B. Theshape of the resist layer 3 is determined by the exposure and thedevelopment conditions, and there is a great variation in the shape ofthe resist layer 3, in particular the shape of the undercuts 3a, 3a.Therefore, it is very difficult to obtain thin-film magnetic headshaving small variations from product to product in terms of the angleand the length L of the slanted plane (i) of the three-layer film 2 andthe thickness and the shape of the longitudinal bias layer 4 in theregion (ii).

(c) Due to the variations in the shape of the resist layer 3, practicalthin-film magnetic heads have a small slanting angle of the plane (i)and a great length L in the X-direction. However, if the length L of theslanted plane (i) increases, the transverse bias layer (soft magneticlayer) 2a will have longer portions at its both ends which do not facethe magnetoresistance effect layer 2c. The portions of the transversebias layer 2a extending in the X-direction beyond the ends of themagnetoresistance effect layer 2c are difficult to magnetize in theY-direction by the magnetoresistance effect layer 2c. As a result, theportions (i) of the transverse bias layer 2a have an independentsensitivity to a leakage magnetic field from a recording medium. Thissensitivity affects the detection current, and can be a cause ofBarkhausen noise.

(d) When the longitudinal bias layer 4 is formed by performingsputtering using the resist layer 3 as a mask, the material for thelongitudinal bias layer has to penetrate into the spaces under theundercuts 3a, 3a of the resist layer 3. Therefore, the deposition rateof the film in these regions is slow, and a great variation occurs inthe thickness of the resultant film. In practical production process ofthin-film magnetic heads, the longitudinal bias layer 4 is deposited,with the low deposition rate and the thickness variation in these spacesbeing taken into account. As a result, the portion of the longitudinalbias layer 4 which is not in contact with the three-layer film 2 (or theportion on which resist layer 3 is not present) has an unnecessarilygreat thickness. This results in a long production time. Furthermore,the total thickness of the magnetic head becomes great. The gap lengthof the thin-film magnetic film is determined by the thickness of thenon-magnetic material layer serving as the lower gap layer and by thethickness of the lower gap layer formed on the three-layer film 2. Inrecent magnetic heads of this type, it is required to reproduce a signalrecorded at a high density and thus a smaller gap length is required.However, if the thickness of the longitudinal bias layer 4 becomesunnecessarily great, the gap length inevitably becomes greater. As aresult, it becomes impossible to meet the requirement of thehigh-density signal reproduction.

On the other hand, the thin-film magnetic head having the structureshown in FIG. 14 has problems described below.

(e) In the conventional structure shown in FIG. 13, since the electrodelayer 5 and the longitudinal bias layer 4 are in contact at the slantedplane (i) with the three-layer film 2, the detection current flows fromthe electrode layer 5 via the longitudinal bias layer 4 not only intothe magnetoresistance effect layer 2c but also partly into thetransverse bias layer 2a.

(f) In order for the free magnetic layer 21 to be magnetized in theX-direction by the longitudinal bias layer 4, it is required that thelongitudinal bias layer 4 can be uniformly magnetized in theX-direction. However, in the regions on the contacting interfaces (V),the thickness (dimension in the X-direction) of the longitudinal biaslayer 4 changes in such a manner that the longitudinal bias layer 4 goesup the spin valve layer SV. As a result, it is difficult to uniformlymagnetize the longitudinal bias layer 4 in the X-direction. One reasonis that in these regions in which the thickness of the longitudinal biaslayer 4 changes in the above-described a manner, when an attempt is madeto magnetize the longitudinal bias layer 4 in the X-direction,demagnetization occurs randomly in the direction and magnitude. Thismakes it difficult to magnetize the longitudinal bias layer 4 in theX-direction. Another reason is that since the longitudinal bias layer 4is in contact with all six layers constituting the spin valve layer SV,the magnetic characteristics of the longitudinal bias layer 4 near thecontacting plane (V) change from part to part in response to the changesin the material of the spin valve layer from layer to layer. For thesereasons, it becomes difficult to uniformly magnetize the longitudinalbias layer 4 into the X-direction. As a result, the degree ofmagnetization of the free magnetic layer 21 in the X-direction into asingle magnetic domain becomes low, and Barkhausen noise becomes great.

(g) The longitudinal bias layer 4 is in contact with both sides of eachof the fixed magnetic layer 23 and the antiferromagnetic layer 24. As aresult, the permanently-magnetized longitudinal bias layer 4 exertsgreat magnetic influences on the fixed magnetic layer 23 andantiferromagnetic layer 24 of the spin valve layer SV. Thus, the fixedmagnetic layer 23 is not uniformly magnetized in the Y-direction andgreat Barkhausen noise occurs.

(h) In order for the free magnetic layer 21 to receive a sufficientlylarge magnitude of magnetic field from the bias layer 4, it is requiredthat the upper surface 4a of the longitudinal bias layer 4 is located ata position higher than the position of the upper surface of the freemagnetic layer 21. To meet this requirement, it is necessary to performa sputtering process for a long time so that the longitudinal bias layer4 has a sufficiently large thickness.

SUMMARY OF THE INVENTION

It is a general object of the present invention to solve the problemsdescribed above. More specifically, it is an object of the presentinvention to provide a thin-film magnetic head having an improvedstructure in which a magnetoresistance effect layer is in contact with alongitudinal bias layer in an improved manner thereby preventingdegradation in characteristics such as an increase in the Barkhausennoise.

It is another object of the present invention to provide a method ofproducing a thin-film magnetic head which makes it possible to preciselyform fine structures such as a contacting part at which a three-layerfilm is in contact with a longitudinal bias layer. It is still anotherobject of the present invention to provide a thin-film magnetic head anda production method thereof which offer stable magnetization of a hardbias layer magnetized thereby ensuring that a free magnetic layer ismagnetized in a more reliable fashion.

In one aspect of the present invention, there is provided a thin-filmmagnetic head including a pair of longitudinal bias layers spaced apredetermined distance apart in the same plane; three layers including,from bottom to top, a magnetoresistance effect layer, a non-magneticlayer, and a transverse bias layer, formed in the space between the pairof longitudinal bias layers; and electrode layers formed on therespective longitudinal bias layers, the electrode layers being disposedat both sides of the three layers.

In the thin-film magnetic head described above, it is desirable thatthere is provided a tantalum film having bcc (body-centered cubic)crystal structure, serving as an underlying film disposed under themagnetoresistance effect layer.

According to another aspect of the present invention, there is provideda method of producing a thin-film magnetic head, including the steps of:forming a longitudinal bias layer and then an electrode layer thereon;partially removing the longitudinal bias layer and electrode layer insuch a manner as to form a narrow space having a predetermined width inthe longitudinal bias layer and electrode layer; successively formingthree layers including, from bottom to top, a magnetoresistance effectlayer, a non-magnetic layer, and a transverse bias layer, in the spaceformed in the above-described partially removing step and also on theelectrode layer; and removing the three layers on the electrode layerexcept for the portion in the above-described space.

According to a further aspect of the invention, there is provided amethod of producing a thin-film magnetic head, including the steps of:forming a longitudinal bias layer; partially removing the longitudinalbias layer in such a manner as to form a narrow space having apredetermined width in the longitudinal bias layer; successively formingthree layers including, from bottom to top, a magnetoresistance effectlayer, a non-magnetic layer, and a transverse bias layer, in the spaceformed in the above-described partially removing step; removing thethree layers on the longitudinal bias layer except for the portion inthe above-described space; and forming an electrode on the longitudinalbias layer.

In the above method, the electrode layer may be formed in such a mannerthat the electrode layer separated from the three layers. Furthermore,in the above method, a layer may be formed on the longitudinal biaslayer using the same material as that of the longitudinal bias layer sothat the above-described layer is in contact with the three layers, andthen the electrode layer is formed on the above-described layer.

According to still another aspect of the invention, there is provided athin-film magnetic head of the spin valve type, including: a freemagnetic layer, a non-magnetic layer, and a fixed magnetic layer; alongitudinal bias layer disposed at both sides of the free magneticlayer, for magnetizing the free magnetic layer into a predetermineddirection; a bias layer disposed on the fixed magnetic layer, formagnetizing the fixed magnetic layer into a direction crossing thedirection in which the free magnetic layer is magnetized; wherein onlythe free magnetic layer is in contact with the contacting interfaces ofthe longitudinal bias layer disposed at both sides of the free magneticlayer.

In the above thin-film magnetic head, it is preferable that thecontacting interfaces be slanted in such a manner that the distancebetween the contacting interfaces increases with the position in thelongitudinal bias layer from bottom to top, and it is also preferablethat the longitudinal bias layer has a substantially constant thicknessin regions near the contacting interfaces and also in the other region.

According to still another aspect of the invention, there is provided amethod of producing a thin-film magnetic head of the spin valve type,including the steps of: forming first a longitudinal bias layer and anelectrode layer; partially removing the electrode layer and longitudinalbias layer; forming a free magnetic layer, a non-magnetic layer, a fixedmagnetic layer, and a bias layer, in the space created by partiallyremoving the electrode layer and longitudinal bias layer, the bias layermagnetizing the fixed magnetic layer into a direction crossing thedirection in which the free magnetic layer is magnetized, wherein thefree magnetic layer is formed in such a manner that only the freemagnetic layer comes in contact with the longitudinal bias layer.

In the thin-film magnetic head of the spin valve type according to thepresent invention, the longitudinal bias layer is in contact at thecontacting interfaces only with the free magnetic layer. This ensuresthat the longitudinal bias layer can magnetize the free magnetic layerin a reliable manner, and also ensures that magnetic layers such as thefixed magnetic layer other than the free magnetic layer are not affectedby the magnetic field from the longitudinal bias layer.

Furthermore, the uniform thickness of the longitudinal bias layerresults in a reduction in the variations in the magnitudes anddirections of demagnetizing field, and thus the longitudinal bias layeris entirely magnetized into the same direction. Furthermore, in thisinvention, it is possible to apply a sufficiently strong of magneticfield to the free magnetic layer without having to increase thethickness of the longitudinal bias layer to an unnecessarily greatvalue.

In the method of producing a thin-film magnetic head according to thepresent invention, a longitudinal bias layer is formed before forming aspin valve layer including free magnetic layer and a fixed magneticlayer. This makes it possible to obtain a longitudinal bias layer havinga uniform thickness. It is desirable that there be provided anunderlying film of Cr (chromium) under the longitudinal bias layerthereby improving the magnetic characteristics of the longitudinal biaslayer. Furthermore, in the production method according to the presentinvention, the longitudinal bias layer is partially removed, and then afree magnetic layer, a non-magnetic layer, and a fixed magnetic layerare successively formed in the space produced by partially removing thelongitudinal bias layer so that only the free magnetic layer is incontact at the contacting interfaces with the longitudinal bias layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1F are cross-sectional views illustrating a production flowof a thin-film magnetic head according to a first embodiment of thepresent invention;

FIG. 2A is a cross-sectional view of a thin-film magnetic head accordingto the first embodiment, and

FIG. 2B is an enlarged cross-sectional view illustrating the partdenoted by IIB in FIG. 2A;

FIGS. 3A to 3F are cross-sectional views illustrating a production flowof a thin-film magnetic head according to a second embodiment of thepresent invention;

FIG. 4A is a cross-sectional view of a thin-film magnetic head accordingto the second embodiment, and

FIG. 4B is an enlarged cross-sectional view illustrating a part of thethin-film magnetic head shown in FIG. 4A;

FIGS. 5A to 5C are cross-sectional views illustrating a production flowof a thin-film magnetic head according to a third embodiment of thepresent invention;

FIG. 6 is an enlarged cross-sectional view partially illustrating thethin-film magnetic head according to the third embodiment;

FIGS. 7A to 7C are cross-sectional views illustrating a production flowof a thin-film magnetic head according to a fourth embodiment of thepresent invention;

FIG. 8 is an enlarged cross-sectional view partially illustrating thethin-film magnetic head according to the fourth embodiment;

FIG. 9 is a cross-sectional view of a thin-film magnetic according to afifth embodiment of the invention;

FIGS. 10A to 10F are cross-sectional views illustrating a productionflow of a thin-film magnetic head according to the fifth embodiment ofthe present invention;

FIG. 11 is a cross-sectional view of a thin-film magnetic according to asixth embodiment of the invention;

FIGS. 12A to 12D are cross-sectional views illustrating a productionflow of a thin-film magnetic head according to a conventional technique;

FIG. 13 is an enlarged cross-sectional view illustrating the partdenoted by XIII in FIG. 12D; and

FIG. 14 is a cross-sectional view of a thin-film magnetic head accordingto another conventional technique.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will be described in further detail with reference tospecific embodiments.

FIGS. 1A to 1F are a cross-sectional views illustrating a productionflow of a thin-film magnetic head according to a first embodiment of thepresent invention. FIG. 2A is a cross-sectional view of a completedthin-film magnetic head, while the part denoted by IIB in FIG. 2A isshown in an enlarged fashion in FIG. 2B.

In the first embodiment, a thin-film magnetic head is produced asfollows. First, as shown in FIG. 1A, a non-magnetic material layer(lower gap layer) 1 as Al₂ O₃ is formed on a lower shielding layer (notshown), and then a longitudinal bias layer 4 and an electrode layer 5are successively formed thereon. In a later process step, a magneticfield is applied to the longitudinal bias layer 4 so that the magneticfield is held in the longitudinal bias layer and thus the longitudinalbias layer acts as a hard bias layer. The longitudinal bias layer 4 ismade of a hard magnetic material such as a Co--Pt alloy. The electrodelayer 5 is made of a material having a low specific resistance such astantalum (Ta) or chromium (Cr).

A resist material is then coated on the electrode layer 5 by means offor example spin coating. The resist material is pre-baked, and thenexposed to light through a mask. The resist is then developed, andfurthermore post-baked so that a resist layer 11 having an opening witha predetermined size is formed as shown in FIG. 1B. The longitudinallayer 4 and the electrode layer 5 are etched by means of for example anion milling technique using the resist layer as a mask so that theportions of the longitudinal bias layer and the electrode layer whichare not covered with the resist layer 11 are removed. The resist layer11 is then removed. As a result, as shown in FIG. 1C, a narrow space orgap having a width equal to the desired track width TW is produced.

Then, as shown in FIG. 1D, a three-layer film 2 having a uniformthickness is formed in the space having the width TW created by removingthe longitudinal bias layer 4 and the electrode 5 and also formed on theupper surface of the electrode layer 5. As shown in an enlarged fashionin FIG. 2B, the three-layer film 2 consists of, from bottom to top, amagnetoresistance effect layer 2c, a non-magnetic material layer (shuntlayer) 2b, and a transverse bias layer (soft magnetic layer: SAL layer)2a. The magnetoresistance effect layer 2c is made of for example aNi--Fe based material, the non-magnetic material layer 2b is made of forexample Ta, and the transverse bias layer 2a is made of for example anFe--Ni--Nb based material.

In the above process, although the three-layer film 2 may be formeddirectly on the non-magnetic material layer (lower gap layer) 1 in thegap-length part TW on which neither the longitudinal bias layer 4 northe electrode layer 5 is present, it is desirable that a tantalum (Ta)film having a bcc crystal structure (body-centered cubic crystalstructure) be formed in the gap-length part TW so that the tantalum filmserves as an underlying layer of the three-layer film 2. If the Ta filmhaving the bcc structure is provided under the magnetoresistance effectlayer (Ni--Fe layer) 2c or the bottom layer of the three-layer film 2,it is possible to reduce the specific resistance of themagnetoresistance effect layer 2c. This reduces the shunting currentflowing into layers other than the magnetoresistance effect layer 2c.

Then, a resist layer 12 is formed on the three-layer film 2 as shown inFIG. 1E. If a resist material is coated on the structure shown in FIG.1D using a spin coating technique or the like, the recessed portion ofthe three-layer film 2 is filled with the resist material, and thus theresist layer 12 having a flat surface is obtained. The resist layer isthen removed except for the portion 12a embedded in the recess as shownin FIG. 1F. In the above process, the resist layer 12 is removed by apredetermined constant thickness using for example an etch backtechnique so that the entire resist layer on the three-layer film 2 isremoved except for the resist portion 12a embedded in the recess.

The portion of the three-layer film 2, which has become exposed afterthe removal of the resist layer 12a, is removed by means of for examplean ion milling technique thereby obtaining a completed thin-filmmagnetic head such as that shown in FIG. 2A.

In the thin-film magnetic head obtained in this way, the three-layerfilm 2 is formed on a slanted plane (iii) formed on each side of thelongitudinal bias layer 4 and the electrode layer 5 while substantiallynone of the three-layer film 2 is formed on the surface of the electrodelayer 5, as shown in FIG. 2B.

The slanted planes (iii) of the longitudinal bias layer 4 and theelectrode layer 5 are formed as follows. First, in the process stepshown in FIG. 1B, the width of the portions to be removed is defined bythe resist layer 11, and then these portions of the electrode layer 5and the longitudinal bias layer 4 are actually removed by means of forexample the ion milling technique. In this process, the gap length TWcan be precisely set to a desired value. Besides, it is easy to controlthe angle of the slanted plane (iii). It is also possible to obtain arather small length L0 of the slanted plane (iii) in the X-direction.

In the structure shown in FIG. 2B, both the magnetoresistance effectlayer 2c and the longitudinal bias layer 4 are located at the bottomlayer, and the magnetoresistance effect layer 2c within the gap lengthTW is parallel to the longitudinal bias layer 4. Therefore, if thelongitudinal bias layer 4 is formed so that it has magnetic anisotropyonly in the X-direction, it becomes possible to effectively apply alongitudinal bias field (hard bias field) in the X-direction to themagnetoresistance effect layer 2c. Thus, it is not necessary for thelongitudinal bias layer 4 to have isotropic magnetic characteristics.This makes it easier to form the longitudinal bias layer 4. Furthermore,the longitudinal bias layer 4 and the magnetoresistance effect layer 2care both located at similar vertical positions. This ensures that thelongitudinal bias layer 4 magnetizes the magnetoresistance effect layer2c in the X-direction into a single magnetic domain.

Furthermore, over the entire slanted plane (iii), there are providedboth the magnetoresistance effect layer 2c and the transverse bias layer2a in parallel positions along the Z-direction. In other words, thetransverse bias layer 2a has no portions protruding in the X-directionbeyond the ends of the magnetoresistance effect layer 2c, unlike theconventional structure shown in FIG. 13. In this structure, even if thetransverse bias layer 2a protrudes beyond the ends of themagnetoresistance effect layer 2c, the length of the protruding portionswill be small enough, since the length L0 of the slanted plane (iii) issmall. Therefore, unlike the conventional thin-film magnetic heads, thetransverse bias layer has no portions which have independent sensitivityto the leakage magnetic field from a magnetic recording medium, and thusit is possible to reduce the Barkhausen noise.

Furthermore, in the slanted plane regions (iii), the end portions of themagnetoresistance effect layer 2c are located on the respective endsides of the longitudinal bias layer 4. This ensures that themagnetoresistance effect layer 2c has good magnetic coupling with thelongitudinal bias layer 4. Therefore, there is no need to form thelongitudinal bias layer 4 to an unnecessarily great thickness. Afterobtaining the structure shown in FIG. 2B, an upper gap layer and anupper shielding layer are formed on both the three-layer film 2 and theelectrode layer 5. Since the longitudinal bias layer 4 is thin, it ispossible to reduce the total layer thickness in the Z-direction. As aresult, it becomes possible to reduce the magnetic gap length determinedby the dimensions along the Z-direction of the upper and lower gaplayers. This means that the resultant thin-film magnetic head canreproduce high-density signals.

In the structure according to the present embodiment, as shown in FIG.2B, both the electrode layer 5 and the longitudinal bias layer 4 are indirect contact with the magnetoresistance effect layer 2c. As a result,the detection current applied to the electrode layer 5 can flow into themagnetoresistance effect layer 2c with little shunting current into thetransverse bias layer 2a.

FIGS. 3A to 3F illustrate a second embodiment of a thin-film magnetichead according to the present invention. FIG. 4A illustrates a completedthin-film magnetic head, and FIG. 4B illustrates, in an enlargedfashion, a part of the thin-film magnetic head shown in FIG. 4A. In eachembodiment described below, the material of each layer is the same asthat of each corresponding layer employed in the first embodimentdescribed above.

In this second embodiment, only a longitudinal bias layer 4 having aconstant thickness is formed on a non-magnetic material layer (lower gaplayer) 1 as shown in FIG. 3A. A resist material is then coated on thislongitudinal bias layer 4 and is subjected to an exposure anddevelopment process so that a resist pattern 11 having an openingsimilar to that shown in FIG. 1B is formed. The portion of thelongitudinal bias layer 4 which is not covered with the resist layer 11is removed by means of etching such as an ion milling technique therebyforming a narrow space (gap) having a predetermined width Tw in thelongitudinal bias layer 4. This width Tw defines the track width. Inthis process using the etching technique with the resist layer 11, it ispossible to precisely control the track width Tw.

Then, as shown in FIG. 3C, a three-layer film 2 is formed on the trackwidth region (space) Tw and also on the upper surface of thelongitudinal bias layer 4. The three-layer film 2 consists of, frombottom to top, a magnetoresistance effect layer 2c, a non-magneticmaterial layer 2b, and a transverse bias layer 2a. The three-layer film2 is formed so that each layer has a predetermined uniform thickness. Asdescribed above with reference to the first embodiment, if a Ta filmhaving the bcc structure is formed in the track width region Tw so thatit serves as an underlying layer of the three-layer film 2, it ispossible to reduce the specific resistance of the magnetoresistanceeffect layer 2c.

A resist material is then coated on the three-layer film 2 over itsentire surface. The resist material is exposed to light through a mask,and then developed so that a resist patten 13 having a width W slightlygreater than the track width Tw is formed as shown in FIG. 3D. Theexposed portion of the three-layer film 2 (i.e., the portion not coveredwith resist layer 13) is removed by means of etching such as an ionmilling technique as shown in FIG. 3E. As a result, the three-layer film2 remains only in the gap (having the width equal to the track width Tw)in the longitudinal bias layer 4 and also in small areas on thelongitudinal bias layer 4.

According to the above process, the three-layer film 2 shown in FIG. 3Ecan be formed so that it has precise dimensions corresponding to thewidth W of the resist pattern 13. As described above, the width W of theresist pattern 13 is slightly greater than the track width Tw so thatthe three-layer film 2 has end portions with a small width L1 extendingbeyond the ends of the track width Tw, wherein the width L1 can becontrolled precisely by controlling the size of the resist pattern 13.

Then as shown in FIG. 3F, a resist layer 14 is formed on the three-layerfilm 2 and also on narrow parts of the longitudinal bias layer 4 at bothsides of the three-layer film 2. This resist layer 14 can be formed asfollows. First, a resist material is coated on the three-layer film 2and on the longitudinal bias layer 4. The resist material is thenexposed to light through a mask and then developed. Then, an electrodematerial is sputtered on the above structure. If the resist layer 14 isthen removed, an electrode layer 5 is formed on the longitudinal biaslayer 4 at locations slightly apart from the three-layer film 2 as shownin FIGS. 4A and 4B.

In the thin-film magnetic head produced in the process described above,since both the longitudinal bias layer 4 and the magnetoresistanceeffect layer 2c are located at the bottom layer, these layers have goodmagnetic coupling, and a hard bias field is effectively applied from thelongitudinal bias layer 4 to the magnetoresistance effect layer 2cthereby ensuring that the magnetoresistance effect layer 2c ismagnetized in the X-direction into a single magnetic domain. The trackwidth Tw can be precisely defined by etching the longitudinal bias layerusing the ion milling technique or the like. Furthermore, there is noneed to form the longitudinal bias layer 4 to an unnecessarily greatthickness, and it is possible to achieve a small gap length.

Furthermore, as shown in FIG. 4B, the three-layer film 2 extends in theX-direction beyond the ends of the track width Tw by an amount of L1 sothat the ends of the three-layer film 2 reach locations on the surfaceof the longitudinal bias layer 4. The length L1 of the portions of thethree-layer film 2 extending beyond the ends of the track width Tw, andthe angle of the slanted planes (iV) at both ends of the three-layerfilm 2 can be controlled precisely by the ion milling (etching) processusing the resist layer 13 shown in FIGS. 3D to 3E. Therefore, unlike theconventional technique shown in FIG. 13, the transverse bias layer (softmagnetic layer) 2a has no parts extending in the X-direction beyond theends of the magnetoresistance effect layer 2c and thus the transversebias layer 2a has no parts having independent sensitivity to a magneticfield. As a result, the Barkhausen noise decreases.

Furthermore, in this thin-film magnetic head, the electrode layer 5 isseparated from the three-layer film 2 so that a detection currentapplied to the electrode layer 5 can flow via the longitudinal biaslayer 4 into the magnetoresistance effect layer 2c with little shuntingcurrent into the transverse bias layer 2a.

FIGS. 5A and 5B are cross-sectional views illustrating a productionprocess of a thin-film magnetic head according to a third embodiment ofthe invention.

FIG. 5C is a cross-sectional view of a completed thin-film magnetichead. A part of the thin-film magnetic head shown in FIG. 5C is shown inan enlarged fashion in FIG. 6.

In this third embodiment, the process steps shown in FIGS. 3A, 3B, and3C are the same-as those in the second embodiment described above. Thatis, after forming a longitudinal bias layer 4 on a non-magnetic materiallayer (lower gap layer) 1, the longitudinal bias layer 4 is partiallyremoved by means of the ion milling technique so that a narrow space(gap) having a width equal to the track width Tw is formed in thelongitudinal bias layer 4. A three-layer film 2 is then formed thereonover the entire surface of the structure. The three-layer film 2consists of a magnetoresistance effect layer 2c located at the bottom, anon-magnetic material layer 2b in the middle, and a transverse biaslayer (soft magnetic layer) 2a at the top. It is also desirable that atantalum film having the bcc structure be formed in the track widthregion Tw so that it serves as an underlying layer of themagnetoresistance effect layer 2c.

Then as shown in FIG. 5A, a resist layer 15 is formed on the three-layerfilm 2. This resist layer 15 is formed by coating a resist materialhaving a predetermined uniform thickness on the three-layer film 2, andthen exposing the resist to deep-UV light through a mask, and finallydeveloping the resist material. The resist layer has undercuts 15a, 15aat its both sides. Then as shown in FIG. 5B, the exposed portion of thethree-layer film 2 (i.e., the portion not covered with resist layer 15)is removed by means of etching such as an ion milling technique. Aelectrode material is then sputtered, and finally the resist layer 15 isremoved.

As a result, as shown in FIG. 5C, an electrode layer 5 is formed on thelongitudinal bias layer 4 wherein the electrode layer 5C has a shapecorresponding to the shape of the undercuts 15a, 15a of the resist layer15, and the both ends of the electrode layer 5 are in contact with therespective ends of the three-layer film 2.

As can be seen from comparison between the structure according to thethird embodiment shown in FIG. 6 and that according to the secondembodiment shown in FIG. 4B, the third embodiment differs from thesecond embodiment only in that the electrode layer is in direct contactwith the three-layer film 2. In the third embodiment, as shown in FIG.6, the track width Tw is defined precisely, and the longitudinal biaslayer 4 can have good magnetic coupling with the magnetoresistanceeffect layer 2c. Furthermore, it is possible to precisely control thelength L1 of the portions of the three-layer film 2 extending beyond theends of the track width Tw and also the angle of the slanted planes (iV)as in the second embodiment shown in FIG. 4.

Furthermore, the transverse bias layer 2a has no portions extendingbeyond the ends of the magnetoresistance effect layer 2c, and adetection current is applied from the electrode layer 5 to themagnetoresistance effect layer 2c so that the detection current flowsthrough the entire length of the magnetoresistance effect layer 2cthereby ensuring that the transverse bias layer 2a is magnetized overits entire length by the magnetic field in the Y-direction from themagnetoresistance effect layer 2c. As a result, unlike the conventionalstructures, the transverse bias layer 2a has no portions havingindependent sensitivity to a magnetic field, and thus it is possible toreduce the Barkhausen noise.

FIGS. 7A and 7B are a cross-sectional view illustrating a productionprocess of a thin-film magnetic head according to a fourth embodiment ofthe invention. FIG. 7C is a cross-sectional view of a completedthin-film magnetic head, wherein a part of the thin-film magnetic headshown in FIG. 7C is shown in an enlarged fashion in FIG. 8.

In this embodiment, the processes shown in FIGS. 7A and 7B are the sameas those shown in FIGS. 5A and 5B.

That is, after forming a longitudinal bias layer 4 on a non-magneticmaterial layer 1, the longitudinal bias layer 4 is partially removed bymeans of the ion milling technique so that the track width Tw is definedin the longitudinal bias layer 4. A three-layer film 2 is then formedthereon. Furthermore, a resist layer 15 having undercuts 15a, 15a isformed, and the three-layer film 2 is etched by the ion millingtechnique using the resist layer 15 as a mask.

In this embodiment, as shown in FIG. 7C, after the three-layer film 2has been partially removed by the ion milling, a hard magnetic material(Co--Pt based material) which is the same as that of the longitudinalbias layer is sputtered so that the longitudinal bias layer 4a is formedon the longitudinal bias layer 4 made of the same material. Then, anelectrode layer 5 is formed thereon.

In the completed structure shown in FIG. 8, the layers 4 and 4a form asingle layer acting as a hard bias layer magnetized in the X-direction.As a result, the magnetoresistance effect layer 2c is magnetized in theX-direction into a single magnetic domain over its entire length. Thus,the Barkhausen noise is reduced to a low level.

The structure shown in FIG. 8 is the same as that shown in FIG. 6 exceptfor the contacting manner of the longitudinal bias layer, and thus thethin-film magnetic head according to the fourth embodiment can offeradvantages similar to those of the third embodiment.

In each of second through fourth embodiments, if an upper gap layer andan upper shielding layer are successively formed on the three-layer film2, a thin-film magnetic head having a final structure is obtained.

FIG. 9 is a front view of a fifth embodiment of a thin-film magnetichead of the spin valve type according to the invention. In thisthin-film magnetic head, a magnetic recording medium moves in theZ-direction, while the leakage magnetic field (external magnetic field)from a magnetic recording medium points in the Y-direction. A lowernon-magnetic layer 20 made of for example Ta (tantalum) is formed on anon-magnetic material layer 1 made of a non-magnetic material such asAl₂ O₃ (aluminum oxide). The lower non-magnetic layer 20 of Ta ensuresthat when a free magnetic layer 21 is formed on it, crystal of the freemagnetic layer 21 is uniformly oriented in the same direction, and thefree magnetic layer 21 has a low specific resistance.

In the track width region Tw, a spin valve layer SV is formed on thelower non-magnetic layer 20 wherein the spin valve layer SV consists offive layers including, from bottom to top, a free magnetic layer 21, anon-magnetic conductive layer 22, a fixed magnetic layer 23, anantiferromagnetic layer 24, and an upper non-magnetic layer 25. The freemagnetic layer 21 and the fixed magnetic layer 23 are made of an Ni--Fe(nickel-iron) alloy, the non-magnetic conductive layer 22 is made of Cu(copper), the antiferromagnetic layer 24 is made of an alloy such asFe--Mn (iron-manganese), Ni--Mn (nickel-manganese), or Pt--Mn(platinum-manganese), and the upper non-magnetic layer 25 is made of forexample Ta. The antiferromagnetic layer 24 serves as a bias layer formagnetizing the fixed magnetic layer 23 in the Y-direction (the upwarddirection perpendicular to the drawing plane) into a single magneticdomain, wherein the fixed magnetic layer 23 is magnetized in theY-direction via the anisotropic exchange coupling at the interfacebetween the antiferromagnetic layer 24 and the fixed magnetic layer 23.

At both sides of the track width region Tw, an underlying film 26 of Cr(chromium). is formed directly on the lower non-magnetic layer 20. Theunderlying film 26 of Cr ensures that a longitudinal bias layer 4 havingimproved magnetic characteristics can be formed on the underlying film26. After forming the longitudinal bias layer 4 of Co--Pt(cobalt-platinum) on the underlying film 26, an electrode layer 5 suchas Cu, Cr, or W (tungsten) is further formed thereon. The contactinginterfaces (Vi) of the longitudinal bias layer 4 and the electrode layer5 are formed in such a manner that the distance between the contactinginterfaces increases with the position from bottom to top. Thelongitudinal bias layer 4 is in contact at the contacting interfaces(Vi) only with the free magnetic layer 21. Therefore, in this structure,unlike the conventional structures, no unnecessary magnetic field fromthe longitudinal bias layer 4 is applied to the fixed magnetic layer 23.Furthermore, since the bias layer 4 is in contact only with the freemagnetic layer 21, the longitudinal bias layer 4 exhibits stablemagnetic characteristics as opposed to the conventional structures shownin FIG. 14 in which the longitudinal bias layer is in contact with aplurality of layers and thus the magnetic characteristics change frompart to part in response to the change in the material from layer tolayer with which the longitudinal bias layer is in contact.

Both the longitudinal bias layer 4 and the electrode layer 5 are formedon the non-magnetic material layer 1 so that they are flat and parallelto each other. The longitudinal bias layer 4 has a substantiallyconstant thickness in the regions near the contacting interfaces (vi) aswell as in the other region. As a result, in the regions near thecontacting interfaces (vi), the demagnetizing field induced in thelongitudinal bias layer 4 has a uniform magnitude and points in the samedirection. This ensures that the longitudinal bias layer 4 is magnetizedin the X-direction.

In the thin-film magnetic head shown in FIG. 9, the longitudinal biaslayer 4 has a uniform thickness and the entire longitudinal bias layer 4is permanently magnetized in the same direction along the X-axis.Furthermore, the longitudinal bias layer 4 is in contact only with thefree magnetic layer 21. Thus, the free magnetic layer 21 is morecompletely magnetized in the X-direction by the longitudinal bias layer4. Furthermore, the fixed magnetic layer 23 is magnetized in theY-direction (the upward direction perpendicular to the drawing plane)via the anisotropic exchange coupling with the antiferromagnetic layer24. The fixed magnetic layer 23 is not affected by the longitudinal biaslayer 4, and thus the fixed magnetic layer 23 is magnetized in theY-direction in a stable fashion. A steady-state current flows from theelectrode layer 5 via the longitudinal bias layer 4 into each layerconstituting the spin valve layer SV in the X-direction. If an externalmagnetic field in the Y-direction is applied, the magnetizationdirection of the free magnetic layer 21 is changed. The electricresistance of the spin valve layer SV changes depending on themagnetization direction of the free magnetic layer 21 and themagnetization direction of the fixed magnetic layer 23. The change inthe electric resistance is detected as the change in the voltage drop,and thus the leakage magnetic field from a magnetic recording medium isdetected. In this thin-film magnetic head, since the magnetizationdirections of the free magnetic layer 21 and the fixed magnetic layer 23are stable as described above, the Barkhausen noise in the detectedsignal is very low and thus it is possible to achieve high-accuracydetection.

FIGS. 10A to 10F illustrate a process flow of the thin-film magnetichead shown in FIG. 9.

First, as shown in FIG. 10A, a longitudinal bias layer 4 and anelectrode layer 5 are successively formed on a non-magnetic materiallayer 1. Although it is not shown in FIG. 10, a lower non-magnetic layer20 is formed on the non-magnetic material layer 1, and an underlyingfilm 26 is formed under the longitudinal bias layer 4. If thelongitudinal bias layer 4 is formed before forming the spin valve layerSV, it is possible to obtain a flat longitudinal bias layer 4 having auniform thickness.

A resist material is then coated on the electrode layer 5 using a spincoating technique. After pre-baking the resist material, the resistmaterial is exposed to light through a mask. The resist is developed andthen post-baked thereby forming a resist layer 11. As a result of theabove process, a window (opening) having a width equal to the trackwidth Tw is formed in the resist layer 11 as shown in FIG. 10B. Theelectrode layer 5 and the longitudinal bias layer 4 are etched by meansof for example ion milling using the resist layer 11 as a mask so thatthe electrode layer 5 and the longitudinal bias layer 4 in the region(track width region) not covered with resist layer 11 are removed.

After completion of the etching process, the resist layer 11 is removed.As a result, the structure shown in FIG. 10C is obtained. In thisstructure, a recessed portion is formed in the electrode layer 5 and thelongitudinal bias layer 4 after the electrode layer 5 and thelongitudinal bias layer 4 have been partially removed, wherein thebottom width of the recessed portion defines the track width Tw.

Then as shown in FIG. 10D, a spin valve layer SV consisting of fivelayers, including a free magnetic layer 21 at the bottom, an uppernon-magnetic layer 25 at the top, and other layers in the middle, isformed by means of sputtering. In the track width region Tw, the spinvalve layer SV is formed on the non-magnetic material layer 1 and thelower non-magnetic layer 20 while the spin valve layer SV is formed onthe electrode layer 5 in the other regions.

Furthermore, a resist layer 12 is formed on the spin valve layer SV overits entire surface in such a manner that the recessed portion or thetrack width region Tw is filled with the resist material as shown inFIG. 10E. The resist layer 12 is then etched by means of for example anetch back technique so that the entire resist layer 12 except in therecessed portion is removed. As a result, as shown in FIG. 10F, therecessed portion is smoothed with the resist material embedded therein,and thus a flat surface structure having substantially no irregularitiesis obtained. The spin valve layer SV is then etched by the ion millingtechnique thereby removing the spin valve layer SV in the exposed areanot covered with resist layer 12 (the entire area except the Tw region).After completion of the etching process, the resist layer 12 remainingin the recessed portion is removed. Thus, a complete thin-film magnetichead having the structure shown in FIG. 9 is obtained.

In the production technique described above with reference to FIG. 10,since the longitudinal bias layer 4 is formed before forming the spinvalve layer SV, it is possible to obtain a longitudinal bias layer 4having a uniform thickness. Furthermore, in this production technique,it is possible to form an underlying film such as Cr 26 beforedepositing th e longitudinal bias layer 4 thereby improving the magneticcharacteristics of the longitudinal bias layer 4. Furthermore, in thisproduction technique, a recessed portion is formed first in thelongitudinal bias layer 4 and the conductive layer 5, and then the spinvalve layer SV is formed in the recessed area. This ensures that thefree magnetic layer 21, which is the bottom layer of the spin valvelayer SV, is in good contact with the longitudinal bias layer 4.

FIG. 11 illustrates a sixth embodiment of a thin-film magnetic headaccording to the invention.

In this thin-film magnetic head, as shown in FIG. 11, there is provideda spin valve layer SV consisting of four layers including a freemagnetic layer 21, a non-magnetic conductive layer 22, a fixed magneticlayer 23 and a bias layer 27. The bias layer 27 is provided to magnetizethe fixed magnetic layer 23 in an upward direction perpendicular to thedrawing plane of FIG. 11, wherein the bias layer 27 is made of α--Fe₂ O₃(iron oxide). The α--Fe₂ O₃ layer magnetizes the fixed magnetic layer 23made of an Ni--Fe alloy into the Y-direction via the anisotropicexchange coupling with the fixed magnetic layer 23. Furthermore, thedirect contact between the α--Fe₂ O₃ layer and the fixed magnetic layer23 enhances the coercive force Hc of the fixed magnetic layer 23, andthus makes it possible for the fixed magnetic layer 23 to be permanentlymagnetized in the Y-direction. In this embodiment, as described above,α--Fe₂ O₃ is employed as the bias layer 27 thereby achieving the stablemagnetization of the fixed magnetic layer 23 and also achieving areduction in the Barkhausen noise.

Furthermore, since α--Fe₂ O₃ is excellent in corrosion resistance, noprotection layer is needed as opposed to the structure shown in FIG. 9in which the upper non-magnetic layer 25 of Ta is provided at the top.This simple structure allows the spin valve layer SV to be formed in ashort time.

What is claimed is:
 1. A method of producing a thin-film magnetic head,comprising the steps of:forming a longitudinal bias layer over a basematerial; forming an electrode layer on the longitudinal bias layer;removing sections of said longitudinal bias layer and electrode layer toform a narrow space having a predetermined width between opposing firstand second portions of said longitudinal bias layer and said electrodelayer; successively forming a magnetoresistance effect layer, anon-magnetic layer, and a transverse bias layer, in said space and alsoon said first and second portions of said electrode layer; and removingsaid magnetoresistance effect, non-magnetic and transverse bias layersfrom the first and second portions of said electrode layer, therebyleaving portions of the magnetoresistance effect, non-magnetic andtransfers bias layers in said space.
 2. A method of producing athin-film magnetic head, comprising the steps of:forming a longitudinalbias layer over a base material; removing a section of said longitudinalbias layer and electrode layer to form a narrow space having apredetermined width between first and second portions of saidlongitudinal bias layer; successively forming a magnetoresistance effectlayer, a non-magnetic layer, and a transverse bias layer in said space;and removing said magnetoresistance effect, non-magnetic and transversebias layers from the first and second portions of said longitudinallayer; thereby leaving portions of the magnetoresistance effect,non-magnetic and transfers bias layers in said space; and forming anelectrode layer over said first and second portions of said longitudinalbias layer.
 3. A method of producing a thin-film magnetic head,according to claim 2, wherein said electrode layer is separated fromsaid magnetoresistance effect, non-magnetic and transverse bias layers.4. A method of producing a thin-film magnetic head, according to claim2, wherein a second longitudinal bias layer is formed on saidlongitudinal bias layer, wherein the second longitudinal bias layer andsaid longitudinal bias layer are formed from a common material, whereinsaid second longitudinal bias layer is in contact with saidmagnetoresistance effect, non-magnetic and transverse bias layers, andwherein the electrode layer is formed on said second longitudinal biaslayer.
 5. A method of producing a thin-film magnetic head, comprisingthe steps of:forming a longitudinal bias layer on a base material;forming an electrode layer on the longitudinal bias layer; removing aportion of said electrode layer and longitudinal bias layer to form aspace; forming a free magnetic layer over the base material in thespace; forming a non-magnetic layer on the free magnetic layer; forminga fixed magnetic layer on the non-magnetic layer; and forming a biaslayer over the fixed magnetic layer such that said bias layermagnetizing the fixed magnetic layer in a direction perpendicular to adirection in which the free magnetic layer is magnetized by thelongitudinal bias layer, wherein only said free magnetic layer of saidfree magnetic layer, said fixed magnetic layer and said non-magneticlayer contacts said longitudinal bias layer.